I am a biochemist, and started using mass spectrometry to solve protein structural problems at the very beginning of the nineties. While preparing my Ph.D. (protein post-translational modifications characterization), I encountered a wealth of such modifications and characterized them finely using mass spectrometry. During this reasearch I lacked a really powerful mass spectrometric data prediction/analysis program. I later decided to write such a program: polyxmass. Happy polyxmass'ing, F.R.